1. Field of the Invention
This invention relates to improvements in line protectors for communication circuits, such as telephone lines and the like, and more particularly, the present invention relates to protectors of the type intended for protection of wire conductors and equipment connected thereto from electrical overvoltage and overcurrent conditions.
2. Discussion of the Relevant Art
Many line protectors and overvoltage devices include what is known as "fail-safe" operation. By this it is meant that the protector should provide a direct metallic current path from the line to ground in the event of an overvoltage/overcurrent condition which would tend to damage the protector. Where a gas tube surge arrester is used in the protector, the provision of a fail-safe mode of operation, external to the gas tube is highly desirable.
Numerous approaches to providing an external fail-safe mechanism in a protector embodying a gas tube surge arrester is shown and described in U.S. Pat. No. 4,533,971 issued to T. J. Smith on Aug. 6, 1985 which is typical of devices presently in use today. This device utilizes a solder disc which melts upon overheating and provides a metallic contact between the line terminal and ground should the overvoltage exist for any length of time.
Other devices utilizing insulated materials which short or disintegrate so that a shorting clip makes contact is disclosed in U.S. Pat. No. 4,212,047 issued to J. Napiorkowski on July 8, 1980 and is considered typical of the devices which have an insulated material disintegrate with overheating. The present invention attempts to overcome shortcomings of the prior art by providing a device which includes a minimum of parts and is reliable.
It is an object of the present invention to provide a line protector of the general type and for the purpose stated that embodies a gas tube surge arrester for protecting the line against overvoltage faults.
It is another object of the present invention to provide a line protector which is relatively inexpensive to manufacture and contains a minimum of parts.
It is a further object of this invention to provide a line protector which embodies a mechanism for effecting a fail-safe operation in the event of an overvoltage/overcurrent line fault.
It is yet another object of the present invention to provide a line protector which provides a metallic conductor to ground as a result of a line fault.